I find this event confusing and am not sure if it following any rules. Please could someone clarify what makes the sprinks come out of their icy cages and if this event is actually functioning the way it is meant to? The problem I see is that if I match three of one colour next to their icy cages nothing happens, but then I match three of a different colour next to them and one dragon gets released. I don't get it. Is this event functioning correctly?
Example, looking at the middle ice box:
I make the blue match below them and nothing happens. The box looks exactly the same:
Now I make the red match next to them and one gets released:
None of this makes sense to me. Any ideas how this works anyone?